Thursday, September 3, 2009

Dealing with small buckthorn: a two-fisted approach

I keep trying to develop the best way of dealing with small buckthorns. These are the ones that either arise from the seed bank, or are resprouts from underground roots or rhizomes. It takes most of the summer for these to grow large enough to find easily, and to think about controlling with herbicide.

In past years, we have waited until early October, when most of the native vegetation has started to senesce, the idea being that then the natives won't be affected by the herbicide. This mostly works, but by then the buckthorn stems are large enough that one needs to use a backpack sprayer. This requires a lot of herbicide, and not all of it can be confined to the buckthorn plants.

This year we are starting earlier, when most of the buckthorn plants are small, and are using spray bottles. I am using a two-fisted approach: one spray bottle with aqueous Garlon 3A for foliar spraying of the very small plants (with blue dye); the other spray bottle with Garlon 4 in bark oil for basal bark treatment of the larger plants (with oil-soluble red dye). By larger plants, I mean plants that are still fairly small, mostly knee-high.

I walk through the area and hone in on every buckthorn plant. These are fairly easy to spot because their leaves are dark green, somewhat shiny, and have a characteristic structure. The small ones, that will be foliar sprayed, need only a couple of brief spritzes from the bottle. The photo to the left shows the situation. The blue dye helps to keep track of which plants have been sprayed. Because it is not necessary to control the spritz very much, I can hold this spray bottle in my left hand.

Unfortunately, most plants are too large for foliar spraying, and must be basal barked. To do this, one must grab the top of the stem and pull it back so that the base is exposed. I can do this with my left hand while holding the foliar spray bottle. The second photo to the left shows a stem that has been treated. The pattern of the oil itself can be seen, and the red dye seems to help. The bit of spray that gets on the leaves also helps to control which plants have already been sprayed.

This approach works but is tedious. I would only suggest it in areas where buckthorn is not too dense. If one has a large patch of solid buckthorn, I would recommend foliar spraying with a backpack sprayer, but waiting until October, when the native vegetation has senesced.

The basal bark treatment can also be done at the same time on sumac, prickly ash, or any other woody plant. In the area we were working in today, there was only scattered sumac, all of which were treated.

This sort of work is what I call "stoop labor". It is not fun, but it does get the job done, and without disturbing significantly the native vegetation. In fact, I have noticed that new natives are becoming established in these areas where buckthorn was once dominant.